.top{
    width: 780px;
    height: 183px;
    float: left;
    margin-bottom: 2px;
}
.banner{
    background:url(./img/banner.jpg);
    width: 780px;
    height: 150px;
    float: left;
}
.nav li{
    float: left;
    width: 78px;
    line-height: 33px;
    background: url(./img/button1.jpg) no-repeat;
    text-align: center;
    color: #064E89;
}
.nav a:hover{
    background: url(./img/button1_bg.jpg);
    display: block;
}